Clearcoating surfaces with holes in it

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  • May 3, 2013 at 5:52 pm #43067

    Is there a way to prevent clearcoat thickening/sagging around a sharp edged hole in a surface. I’m thinking about putting tape on the back, covering the hole. Could this help?

    May 4, 2013 at 3:30 am #43076

    I always put tape on the back of a hole ( if I have access) or fill the hole with foam tape. I don’t think it really helps with preventing runs, but it helps prevent junk from blowing out onto the panel and stops over spraying from going where it shouldn’t.

    All I can suggest is adjusting your technique. Maybe back off just a hair when clearing and/ or allow a little more flash time between coats. A slightly faster clear ( or reducer may help).

    I usually don’t have too many issues like this, but I certainly do once in a while and can appreciate your frustration.

    May 4, 2013 at 5:07 am #43077

    That’s the surface tension properties of the paint, or edge crawling in your instance. This phenomenon can also be winessed in a water level higher than a glass rim. Some clears, such as PPG 2021 do it more than others. Tape may reduce it slightly but not eliminate it. The edge is the source of the issue. A brief description of crawling is here: Don’t hammer on the clear with those producing it more.

    May 4, 2013 at 5:37 am #43078

    Thinking deeper about it, maybe a solution can be found in the prep work. Sand the edges less sharp, so the clear can flow slightly around the corner, into the hole so to speak.

    I think the problem is that next to sharp edges, the clear can’t flow. It can, but only to one side where it collides with the clear that tries to flow in the direction of the edge = thickening.

    May 4, 2013 at 5:46 am #43079

    Well that depends on the thickness of the material, and sheetmetal is not thick enough to provide what you suggest. Even panel edges will do it and nothing can be done to them. Shoot bikes and you’ll find it happening more often with that tin. You have to monitor your application to reduce, control or eliminate it. The flow of which you speak is what I mentioned. More data about it’s occurance can be studied if one desires.

    May 4, 2013 at 6:02 am #43080

    edges of a glass are rounded yet water will still hole on higher than the rim as Scott says. your prep work isnt gonna help fix the problem. gotta work on your application

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